Mono- and heteroligand iron(II) complexes with tris(3,5-dimethylpyrazol-1-yl)methane

Coordination compounds of iron(II) thiocyanate with tris(3,5-dimethylpyrazol-1-yl)methane (HC(3,5-Me₂Pz)₃), [Fe(HC(3,5-Me₂Pz)₃)₂](NCS)₂] (I) and [Fe(HC(3,5-Me₂Pz)₃)(Рhz)(NCS)₂] · H₂O (II), where Рhz is phthalazine, are synthesized. The complexes are studied by X-ray diffraction analysis, diffuse reflectance and IR spectroscopy, and static magnetic susceptibility measurements. The single crystals are obtained, and the molecular and crystal structures of complex II and compounds [Fe(HC(3,5-Me₂Pz)₃)(3,5-Me₂Pz)(NCS)₂] · С₂H₅OH (III), where 3,5-Me₂Pz is 3,5-dimethylpyrazole, and [Fe(HC(3,5-Me₂Pz)₃)₂][Fe(HC(3,5-Me₂Pz)₃)(NCS)₃]₂ (IV) are determined (CIF files CCDC 1415452 (II), 1415453 (III), and 1415454 (IV)). The study of the temperature dependence μ_eff(Т) in a range of 2–300 K shows exchange interactions of the antiferromagnetic character between the iron(II) ions in complexes I and II.     

Synthesis and spectroscopic characterization of new organotin(IV) complexes with bis(3,5-dimethylpyrazol-1-yl)dithioacetate

New organotin(IV) derivatives containing the anionic ligand bis(3,5-dimethylpyrazolyl)dithioacetate [L₂CS₂]^? have been synthesized by reaction of SnR _n X_{4? n} (R?=?Me, Ph, ⁿ Bu or Cy; n?=?1–3) acceptors and Li[L₂CS₂]. Mononuclear complexes of the type [L₂CS₂]R _n SnCl_{4? n ?1}} have been obtained and fully characterized by elemental analyses and FT-IR in the solid state, and by NMR (¹H and ¹¹⁹Sn) spectroscopy, conductivity measurements and electrospray ionization mass spectrometry (ESI-MS) in solution. ESI-MS spectra of methanol solutions of diorganotin derivatives, recorded with fragmentor potentials of 0, 50, 100 and 150?V, show the occurrence at 150?V of peaks attributable to the loss of the CS₂ group from the ligands and the formation of stable tetraorganodistannoxane species.     

Synthesis, characterization, and electrochemistry of cis-oxothio- and cis-bis(thio)tungsten(VI) complexes of hydrotris(3,5-dimethylpyrazol-1-yl)borate

The complexes TpWO2X react with sulfiding agents such as B2S3 or P4S10 to give the oxothio- and bis(thio)tungsten(VI) complexes TpWOSX (X = Cl(-)) and TpWS2X [X = Cl(-), S2PPh2(-); Tp = hydrotris(3,5-dimethylpyrazol-1-yl)borate]. The reaction of TpWS2Cl with (i) PPh3 in pyridine and (ii) dimethyl sulfoxide affords TpWOSCl in good overall yield. The chloro complexes undergo metathesis with alkali metal salts to yield species of the type TpWOSX and TpWS2X [X = OPh(-), SPh(-), SePh(-), (-)-mentholate]. The diamagnetic complexes exhibit NMR spectra indicative of C(1) (TpWOSX) or C(s) (TpWS2X) symmetry and IR spectra consistent with terminal oxo and thio ligation (nu(W=O), 940-925 cm(-1); nu(W=S) or nu(WS2), 495-475 cm(-1)). Crystals of (R,S)-TpWOS[(-)-mentholate] are monoclinic, space group P2(1), with a = 11.983(2) A, b = 18.100(3) A, c = 13.859(3) A, beta = 91.60(2) degrees, V = 3004.6(8) A(3), and Z = 4. Crystals of TpWS2(OPh)-CH2Cl2 are orthorhombic, space group Pbca, with a = 16.961(4) A, b = 33.098(7) A, c = 9.555(2) A, V = 5364(2) A(3), and Z = 8. The mononuclear, distorted-octahedral tungsten centers are coordinated by a tridentate Tp ligand, an alkoxy or aryloxy ligand, and two terminal chalcogenide ligands. The average W=O and W=S distances are 1.726(7) and 2.125(2) A, respectively, and the O=W=S and S=W=S angles 102.9(3) and 102.9(1) degrees, respectively. The tungsten and sulfur X-ray absorption spectra of TpWOSCl and TpWS2Cl are consistent with the presence of terminal pi-bonded thio ligands in both complexes. The thio complexes generally undergo a reversible one-electron reduction at potentials significantly more positive than their oxo analogues. The chemical, spectroscopic, and electrochemical properties of the complexes are heavily influenced by the presence of W=S pi frontier orbitals.     

Dinuclear copper(I) complexes of tris(3,5-dimethylpyrazol-1-yl)methane: Synthesis, structure, and reactivity

The reaction of [Cu(NCMe)₄](BF₄) with equimolar amounts of the tris(substituted-pyrazolyl)methane ligand HCPz₃ or HC(3,5-Me₂Pz)₃ yields the respective salts [Cu(HCPz₃)(NCMe)](BF₄) (1a) or [Cu(HC(3,5-Me₂Pz)₃)(NCMe)](BF₄) (1). The acetonitrile ligand of 1 can be replaced by prazine, 4,4′-dipyridine or 1,4-diisocyanobenzene to yield related mononuclear complexes [Cu(HC(3,5-Me₂Pz)₃)(pyrazine)](BF₄) (2), [Cu(HC(3,5-Me₂Pz)₃)(4,4′-bipyridine)] (BF₄) (3) or [Cu(HC(3,5-Me₂Pz)₃)(1,4- CNC₆H₄NC)](BF₄) (7), respectively. A series of binuclear copper(I) complexes {[Cu(HC(3,5-Me₂Pz)₃)]₂(μ -BL)}(BF₄)₂ (4, BL = pyrazine; 5, BL = 4,4′-dipyridine; 8, BL = 1,4-diisocyanobenzene) were prepared by treating equal molar ratio of 1 with related mononuclear complexes 2, 3 and 7. In addition, binuclear copper(I) complexes were also prepared from treatment of 2 equiv of 1 with the related bridge ligand. Both of 4 and 5 reformed mononuclear starting complex 1 in acetonitrile solution. However, the more robust complex 8 was stable in acetonitrile solutions. The structure of complexes 1a, 4, 5, and 7 were confirmed by X-ray crystallography. The redox properties of 4 and 8 were examined by cyclic voltammetry and exhibited two quasi-reversible waves suggesting that no significant structural reorganization occurs during the redox process on the electrochemical time scale.     

Spin crossover in the coordination compounds of iron(II) with tris(3,5-dimethylpyrazol-1-yl)methane

Iron(II) complexes with tris(3,5-dimethylpyrazol-1-yl)methane {HC(3,5-Me₂Pz)₃} of the composition [Fe{HC(3,5-Me₂Pz)₃}₂]Am · nH₂O (A = Cl^? (I), ClO ₄ ^? (II), SO ₄ ^2? (III), CF₃SO ₃ ^? (IV), m = 1, 2, n = 0.1) are synthesized. The compounds are studied by static magnetic susceptibility, IR and diffuse reflectance spectroscopy, and X-ray structure analysis. The crystal structures of two polymorphous modifications of the [Fe{HC(3,5-Me₂Pz)₃}₂](ClO₄)₂ (IIa and IIb) and [Fe{HC(3,5-Me₂Pz)₃}₂](CF₃SO₃)₂ (IV) complexes are determined. The temperature dependence ??_eff(T) shows that the spin crossover ¹ A ₁ ai ⁵ T ₂ is observed in the polycrystalline phase of complex I and in one of the single-crystal phases of complex II (IIa) and is accompanied by thermochromism (the change of the dark pink color ai to white).     

Thermodynamic properties of complex compounds of iron(II) nitrate with tris(3,5-dimethylpyrazol-1-yl)methane

The temperature dependence of the heat capacity of a complex compound of iron(II) nitrate with tris(3,5-dimethylpyrazol-1-yl)methane is studied by adiabatic calorimetry in the range of 100–300 K. A specific heat anomaly is found and localized in the temperature range corresponding to the sharp spin transition ¹ A ₁ ? ⁵ T ₂ with hysteresis on the temperature dependence of the magnetic susceptibility. The effects of cooperative interaction are revealed on the basis of thermodynamic and magnetochemical data, using two widely used models of spin transition.     

Synthesis, spectroscopic characterization, X-ray structure and DFT calculations of rhenium(III) complex with bis(3,5-dimethylpyrazol-1-yl)methane

[ReCl₃(MeCN)(PPh₃)₂] reacts with bis(3,5-dimethypyrazol-1-yl)methane (bdmpzm) in acetone to give [ReCl₃(bdmpzm)(PPh₃)]. The compound has been studied by IR, UV–Vis spectroscopy and X-ray crystallography. The molecular orbital diagram of [ReCl₃(bdmpzm)(PPh₃)] has been calculated with the density functional theory (DFT) method.     

Synthesis,spectroscopic characterization,X-ray structure and DFT calculations of five-coordinated chlorocopper(II) complex with bis(3,5-dimethylpyrazol-1-yl)methane

The reaction of copper dichloride dihydrate and bis(3,5-dimethylpyrazol-1-yl)methane affords [Cu{H₂C(3,5-Me₂pz)₂}₂Cl]Cl · 3H₂O. The compound has been studied by IR, UV–Vis spectroscopy and X-ray crystallography. The electronic structure of the [Cu{H₂C(3,5-Me₂pz)₂}₂Cl]⁺ cation has been calculated with the density functional theory (DFT) method. The spin-allowed doublet–doublet electronic transitions of [Cu{H₂C(3,5-Me₂pz)₂}₂Cl]⁺ have been calculated with the time-dependent DFT method, and the UV–Vis spectrum of the title compound has been discussed on this basis.     

Tricarbonyl rhenium complexes of bis(pyrazol-1-yl)methane and bis(3,5-dimethylpyrazol-1-yl)methane – Synthesis,spectroscopic characterization,X-ray structure and DFT calculations

Two novel tricarbonyl rhenium complexes based on the bidentate heterocyclic N–N ligands [bis(pyrazol-1-yl)methane(bpzm) and bis(3,5-dimethylpyrazol-1-yl)methane(bdmpzm)] have been synthesized by heating at reflux [Re(CO)₅Cl] with the appropriate N–N ligand in toluene. The compounds have been characterized by IR and UV–Vis spectroscopy and X-ray analysis. Density functional theory (DFT) and time-dependent (TD) DFT calculations have been carried out for the [Re(CO)₃(bdmpzm)Cl] complex.     

Synthesis and reactivity of bis(3,5-dimethylpyrazol-1-yl)ethane tetracarbonylmolybdenum and tungsten X-ray crystal structureof bis(3,5-dimethylpyrazol-1-yl)ethane tetracarbonyltungsten

Bis(3,5-dimethylpyrazol-1-yl)ethane tetracarbonylmolybdenum (1a) and tungsten (1b) have been synthesized by the direct reaction of bis(3,5-dimethylpyrazolyl)ethane (bmpze) with M(CO)₆ (M = Mo or W). The molecular structure (1b), determined by x-ray crystallography, showed the seven-membered ring W–N–N–C–C–N–N to be in the boat conformation. Upon treatment with RSnCl3 (R=Ph or Cl) in CH₂Cl₂ at room temperature, complexes (1a) and (1b) gave the seven-coordinate oxidative-addition products [(bmpze)M(CO)₃(SnCl₂R)Cl] [M = Mo, R = Ph, (2a); M = W, R=Ph, (2b); M = Mo, R = Cl, (2c); M = W, R = Cl, (2d)]. When complexes (1b) and (2b) were heated under reflux with 1,2-bis(diphenylphosphino)ethane (dppe), the ligand, bmpze, in these complexes was easily removed. The novel compounds were characterized by ¹H-n.m.r., i.r. and elemental analysis.     

Rhodium(I) complexes with pyridazine, 4,6-dimethyl-pyrimidine, 4,6-bis(3,5-dimethylpyrazol-1-yl)pyrimidine, 3,6-bis(3,5-dimethylpyrazol-1-yl)pyridazine and 3-(3,5-dimethylpyrazol-1-yl)-6-chloropyridazine

The synthesis and properties of rhodium(I) complexes of formulae [“RhCl(diolefin)”₂(L)] (or [Rh(Cl(diolefin)(L)]), and [Rh(diolefin)(L)]_n(ClO₄)_n are reported. These complexes react with carbon monoxide to yield the related carbonyl derivatives. Ligands used were pyridazine, 4,6-dimethyl-pyrimidine, 4,6-bis(3,5-dimethylpyrazol-1-yl)pyrimidine, 3,6-bis(3,5-dimethylpyrazol-1-yl)pyridazine and 3-(3,5-dimethyl-pyrazol-1-yl)-6-chloropyridazine. Related iridium(I) and gold(I) compounds are also reported.     

Paramagnetic oxotungsten(V) complexes containing the hydrotris(3,5-dimethylpyrazol-1-yl)borate ligand

Sky-blue Tp*WOCl(2) has been synthesized from the high-yielding reaction of Tp*WO(2)Cl with boron trichloride in refluxing toluene. Dark-red Tp*WOI(2) was prepared via thermal decarbonylation followed by aerial oxidation of Tp*WI(CO)(3) in acetonitrile. From these precursors, an extensive series of mononuclear tungstenyl complexes, Tp*WOXY [X = Cl(-), Y = OPh(-), SPh(-); X = Y = OPh(-), 2-(n-propyl)phenolate (PP(-)), SPh(-), SePh(-); XY = toluene-3,4-dithiolate (tdt(2-)), quinoxaline-2,3-dithiolate (qdt(2-)), benzene-1,2-diselenolate (bds(2-)); Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate], was prepared by metathesis with the respective alkali-metal salt of X(-)/XY(2-) or (NHEt(3))(2)(qdt). The complexes were characterized by microanalysis, mass spectrometry, electrochemistry, IR, electron paramagnetic resonance (EPR), and electronic absorption spectroscopies, and X-ray crystallography (for X = Y = OPh(-), PP(-), SPh(-); XY = bds(2-)). The six-coordinate, distorted-octahedral tungsten centers are coordinated by terminal oxo [W≡O = 1.689(6)-1.704(3) ?], tridentate Tp*, and monodentate or bidentate O/S/Se-donor ligands. Spin Hamiltonian parameters derived from the simulation of fluid-solution X-band EPR spectra revealed that the soft-donor S/Se ligand complexes had larger g values and smaller (183)W hyperfine coupling constants than the less covalent hard-donor O/Cl species. The former showed low-energy ligand-to-metal charge-transfer bands in the near-IR region of their electronic absorption spectra. These oxotungsten(V) complexes display lower reduction potentials than their molybdenum counterparts, underscoring the preference of tungsten for higher oxidation states. Furthermore, the protonation of the pyrazine nitrogen atoms of the qdt(2-) ligand has been examined by spectroelectrochemistry; the product of the one-electron reduction of [Tp*WO(qdtH)](+) revealed usually intense low-energy bands.     

Syntheses, structures, and magnetic characterization of dicyanometalate(II) building blocks: [NEt4][(Tp*)MII(CN)2] [MII = Cr, Co, Ni; Tp* = hydridotris(3,5-dimethylpyrazol-1-yl)borate

The syntheses and structures of three dicyanometalate(II) complexes, [NEt(4)][(Tp*)M(II)(CN)(2)].nMeCN.(1/2)Et(2)O (M(II) = Cr, 1, n = (1/2); Co, 2, n = 1; Ni, 3, n = 1) are described; magnetic studies indicate that 3 is diamagnetic while 1 and 2 are paramagnetic high- and low-spin S = 2 and (1/2) complexes, respectively.     

三(3,5-二甲基吡唑)氢合硼酸钾及双[三(3,5-二甲基吡唑)]氢合硼酸根合铜(II)的合成和晶体结构

为研究吡唑硼类配体的配位行为, 合成了三(3,5-二甲基吡唑氢合硼酸钾[KHB(C~5H~7N~2)~3], 简称(KL)和双[三(3,5-二甲基吡唑)氢合硼酸根]合铜(II){Cu[HB(C~5H~7N~2)~3]~2}, 简称(CuL~2), 并测定了它们的晶体结构。化合物KL属空间群P2~1/n。a=1.0527(8), b=0.9464(3), c=1.7730(9)nm, β=94.51(5)°,Z=4, D~c=1.268g.cm~-~3, R=0.079。化合物CuL~2属空间群PI, a=0.8768(1),b=1.0170(2), c=1.0859(1)nm, α=62.45(1),β=83.78(1), γ=78.52(1)°, Z=2,D~c=1.298 g.cm~-~3, R=0.062。晶体结构测定结果表明: 化合物KL由钾离子和配体负离子组成, K~+与配体L中的B原子相距0.3634nm, 在配体负离子中B原子与三个吡唑环的N原子及H原子形成四面体构型。化合物CuL~2由孤立分子组成, 铜离子处于分子的对称中心且与两个配体分子中的六个N原子形成六配位的八面体构型, 并表现出明显的Jahn-Teller效应。     

Copper(II) complexes with bis(4-iodo-3,5-dimethylpyrazol-1-yl)methane: Synthesis,spectroscopic study,and crystal structure

New complexes of copper(II) nitrate, chloride, tetrafluoroborate, perchlorate, and perrhenate with bis(4-iodo-3,5-dimethylpyrazol-1-yl)methane (L) were obtained. The molecular and crystal structures of [CuL(H₂O)(NO₃)₂] · (CH₃)₂CO, [CuL₂(H₂O)][CuL₂Cl][CuCl₄], [CuL₂](BF₄)₂ · (CH₃)₂CO, and [CuL₂(H₂O)](ClO₄)₂ · (CH₃)₂CO were determined by X-ray diffraction analysis. In all the complexes, L was found to serve as a chelating bidentate ligand through the N² and N^2′ atoms of its pyrazole rings to form a six-membered chelate ring.     

Cu(II), Cd(II) and Ni(II) azide complexes incorporating bis(3,5-dimethylpyrazol-1-yl)methane - Synthesis, spectroscopic characterisation, X-ray studies and magnetic properties

Three novel compounds [Cu₂(μ_1,1-N₃)₂(N₃)₂(bdmpzm)₂] (1) [Cd(N₃)₂(bdmpzm)]_n (2) and [Ni(N₃)₂(bdmpzm)₂] (3) have been synthesised and characterised structurally and spectroscopically. The structure 1 consists of a neutral dinuclear [Cu₂(μ_1,1-N₃)₂(N₃)₂(bdmpzm)₂] entities, compound 2 has one-dimensional zigzag chain structure extending along the crystallographic direction [1 0 0] with alternating di-μ_1,1-N₃ and di-μ_1,3-N₃ bridges, and 3 is a mononuclear complex. The experimental studies on the nickel(II) complex have been accompanied computationally by the density functional theory (DFT) calculations.     

Synthesis, characterization and structures of 2-(3,5-dimethylpyrazol-1-yl)ethylseleno derivatives and their probable glutathione peroxidase (GPx) like activity

A series of 2-(3,5-dimethylpyrazol-1-yl)ethylseleno derivatives has been synthesized. The glutathione peroxidase like catalytic activity of these compounds has been studied in a model system, in which reduction of hydrogen peroxide with dithiothreitol (DTT(red)), in the presence of an organoselenium compound was investigated by (1)H NMR spectroscopy. All these compounds exhibit GPx like catalytic activities and the catalytic reaction proceeds through a selenoxide intermediate, identified by (77)Se{(1)H} NMR spectroscopy.     

Synthesis,spectroscopic and magnetic characterization of some iron(III)-nucleotide compounds

Summary Magnetic moments and⁵⁷Fe M?ssbauer spectra at various temperatures of polycrystalline samples of some Fe^III-nucleotide compounds are described and have been characterized by u.v.-visible and fluorescence spectroscopy. Conclusions regarding the binding of iron(III) to nucleic acids are discussed.     

Synthesis of a photoswitchable azobenzene-functionalized tris(indazol-1-yl) borate ligand and its ruthenium(II) cyclopentadienide complex

In this paper, the design and synthesis of a new indazole bearing a photoisomerizable fragment at its 4-position are presented as well as the photoisomerization studies on both the indazole precursor and the final ruthenium model complex. It was obtained after five steps, the last one being the cleavage of the indazole protecting group. Reaction of 1 equiv of this functionalized indazole with 2 equiv of plain indazole and dibromophenylborane gave access to a mixture of four tripodal ligands of the tris(indazolyl)borate family. In a last step, complexation of this mixture with [RuCp(CH₃CN)₃]PF₆ yielded the corresponding ruthenium complexes from which the target ruthenium complex coordinated to a dissymmetric azobenzene-functionalized tripodal ligand was successfully isolated. Photoisomerization occured reversibly upon irradiation with UV light at 365 nm.